The role of six indigenous macrophytes (Cypreus grandis, C. dubis, Kyllinga erectus, Phragmites mauritianus, Typha domingensis and T. capensis) was investigated for nitrogen removal in horizontal subsurface flow constructed wet- lands at the University of Dar es Salaam in Tanzania receiving waste stabilization ponds effluent. Seven horizontal sub- surface flow constructed wetlands were fed with the same source of domestic wastewater, where six of them were planted with a monoculture macrophytic species while the seventh was not planted and it acted as a control cell. On alternatedays' basis for twenty eight weeks both the influent and effluent water samples from each cell were collected and sent to the laboratory for ammonia-N, nitrate-N and Total Kjeldahl-N analysis. Nitrogen bioaccumulation and plant biomasses were analyzed during the transplanting time, after ten weeks and after flowering. Temperature, pH and plant heights were de- termined in situ. Results show that overall nitrogen removal was through denitrification where K.erectus performed better (75.59%) than the rest.Since P.mauritianus(74.37% )established well and had the longest growing period after harvest useso therefore it was selected as the best macrophyte. More research needs to be done prior to making a final decision on the use of any of these macrophytes for nitrogen removal depending on the weather and soils of the specific area.
